1. Field of the Invention
The present invention relates to an absorbent article, such as a sanitary napkin, a disposable diaper and so forth, using a surface layer formed of continuous filaments and an absorbent sheet formed of superabsorbent polymer.
2. Description of the Related Art
An absorbent article, such as a sanitary napkin, a disposable diaper or the like, is provided with an absorbent layer between a liquid permeable surface sheet and a liquid impermeable backing sheet.
In order to make an absorbent article thin type with large liquid absorbing capacity, the absorbent layer is formed of a fibrous absorbent core and superabsorbent polymer (SAP). Conventionally, used is granular superabsorbent polymer, which is arranged on the surface of the fibrous absorbent core or contained in the fibrous absorbent core. When such granular superabsorbent polymer is used, it is required to uniformly disperse and retain the polymer without causing local concentration.
To this end, for example Japanese Unexamined Patent Publication No. Heisei 5-38350 discloses an absorbent core which is prepared by applying an adhesive in spots, lines or curved lines onto an absorbent material, dispersing granular superabsorbent polymer thereon, stacking another absorbent material thereon, and compressing the stack to be integrated.
On the other hand, in Japanese Unexamined Patent Publication No. Heisei 9-156014, there is disclosed an absorbent sheet of aggregate of fibers, in which granular superabsorbent polymer is bonded and retained on fibers within the absorbent sheet.
However, in both of the above-identified publications, since granular superabsorbent polymer is maintained within a fibrous absorbent core, the superabsorbent polymer is not always distributed uniformly in an absorbent layer to possibly cause local concentration. Therefore, the liquid absorbing performance is liable to fluctuate from place to place in the absorbent layer.
In the absorbent core disclosed in the Japanese Unexamined Patent Publication No. Heisei 5-38350, moreover, an adhesive is employed for fixing the granular superabsorbent polymer within the fibrous absorbent core. Since the adhesive is applied in spots, lines or curved lines, it is not possible to certainly fix all superabsorbent polymer. Furthermore, since the adhesive is remained within the fibrous absorbent core, such residual adhesive may possibly lower liquid permeability.
Next, in the absorbent sheet disclosed in Japanese Unexamined Patent Publication No. Heisei 9-156014, since the granular superabsorbent polymer is fusion-bonded on the fibers, there is a possibility that absorbing performance of the superabsorbent polymer may be lowered by fusion-bonding.
Furthermore, in the conventional absorbent article, a surface sheet, which is formed of a liquid permeable non-woven fabric or a synthetic resin film formed with a large number of openings, is provided on the fibrous absorbent core thus formed, and the fibrous absorbent core and the surface sheet are partially adhesive-bonded. Accordingly, adhesive-bonding process of the fibrous absorbent core and the surface sheet becomes necessary to increase process step. Furthermore, due to presence of an adhesive, liquid permeability of the surface sheet is degraded.
Moreover, the surface sheet thus formed of the liquid permeable non-woven fabric or the synthetic resin film having the openings causes the resistance as contacting with the skin of a wearer. That is, the conventional surface sheet does not provide good contact feeling.
The present invention has been worked out in view of the drawbacks set forth above. Therefore, it is an object of the present invention to provide an absorbent article in which superabsorbent polymer can be uniformly distributed and certainly fixed with respect to a fibrous absorbent core, which can eliminate necessity of use of adhesive which would otherwise lower liquid absorbing performance, and which can provide soft contact feeling to the skin of a wearer.
According to the present invention, there is provided an absorbent article comprising:
a liquid permeable surface layer formed of continuous filaments individually extending over the entire length of the surface layer, the continuous filaments including at least heat-fusible continuous filaments;
a backing sheet; and
a fibrous absorbent core located between the surface layer and the backing sheet and containing heat-fusible fibers,
wherein between the surface layer and the fibrous absorbent core, disposed is an absorbent sheet which is formed of superabsorbent polymer to have a plurality of through passages, and the surface layer and the fibrous absorbent core are partially fusion-bonded to each other via the through passages formed in the absorbent sheet for retaining the absorbent sheet between the surface layer and the fibrous absorbent core.
For example, the absorbent sheet may be formed with superabsorbent polymer fibers, and the surface layer and the fibrous absorbent core may be fusion-bonded via gaps defined between fibers of the absorbent sheet. Alternatively, the absorbent sheet may be a superabsorbent polymer film, and the surface layer and the fibrous absorbent core may be fusion-bonded via openings or cuts formed in the film.
Preferably, the heat-fusible continuous filaments in the surface layer and the heat-fusible fibers in the fibrous absorbent core are fusion-bonded at a plurality of fixing lines, which extend in a direction intersecting a direction along which the continuous filaments extend and are spaced apart from each other in the direction along which the continuous filaments extend.
In the present invention, the absorbent sheet formed of the superabsorbent polymer in the form of fibers or a film is firmly maintained between the surface layer and the fibrous absorbent core, so that the superabsorbent polymer is uniformly distributed in a liquid absorbing region. Here, no adhesive is required for maintaining the superabsorbent polymer. Therefore, the absorbent article can exhibit high liquid absorbing performance over a large area.
In addition, since the fibrous absorbent core and the surface layer are preliminarily integrated, the absorbent article can be simply manufactured.
Furthermore, since the surface layer is formed with the continuous filaments, it becomes so bulky as to have low density, to thereby provide soft contact feeling to the skin of a wearer. Especially since the continuous filaments extend over the entire length of the surface layer, no fiber end appears on the surface thereof to provide smooth feeling.